The present invention relates to a new and improved high density, low pitch miniaturized edge card connector. More particularly, it relates to an edge card connector including a two-part housing assembled from hermaphroditic or complementary halves characterized by improved control over manufacturing tolerances and a plurality of substantially stress resistant metallic terminals positively positioned and mounted in the housing providing improved pitch control in mating and electrical reliability in use.
Edge connectors include a nonconductive housing having an elongated slot dimensioned to receive an edge of a circuit card or the like. The edge connector includes a plurality of electrical contacts disposed to be aligned with the conductive leads on the circuit card. To ensure good electrical connection, the various contacts must be urged against the conductive leads of the circuit card upon the insertion of the circuit card into the connector.
The edge connector typically is mounted to a printed circuit board on which an array of conductive strips is printed or otherwise disposed. A portion of each contact in the edge connector is electrically connected to the conductive strips on the printed circuit board. For example, each contact of the edge connector may include a solder tail which extends through an aperture in the printed circuit board. The solder tails then may be connected electrically to the conductive strips on the printed circuit board to which the edge connector is mounted.
The housing of the typical prior art edge connector is molded as a unitary member to include both the slot for the circuit card and a plurality of elongated receptacles for receiving at least portions of each electrical contact. The contact receptacles may extend into the connector from the side opposite the slot. In this type of prior art edge connector, the electrical contacts are inserted into the connector housing in one direction, while the circuit card is inserted in an opposite direction. In other embodiments of the prior art edge connector, the various electrical contacts are inserted into the housing in generally the same direction as the card.
In recent years, there has been a remarkable trend toward miniaturization of electrical components. This trend has required the electronics industry to produce both smaller electrical contacts and smaller housings. For example, many specifications require edge connectors with a plurality of contacts disposed at 0.050 inch center to center spacings. Many of these very small edge connectors are used for double sided circuit cards. Thus, within a very small space (e.g. 0.050 center to center spacing) it is necessary to provide two contacts. It is also necessary to ensure that both the housing and each of the contacts is precisely mounted to achieve the required contact pressure against the conductive strips on the circuit card.
The miniaturization of electrical components has contributed to substantial problems in manufacturing edge connectors. In particular, the prior art edge connector of unitary construction has been injection molded in an apparatus having core pins to define the respective receptacles for the individual contacts. However, the small contacts disposed at very small center to center spacings require core pins with a very long length for their cross-sectional area. As a result, the core pins are easily damaged or deformed during high pressure injection molding processes. The damaged core pins produce defective connectors. Additionally, it is difficult to insert the very small electrical contacts in a longitudinal direction into the edge connector. Even small misalignments between the contacts and the connector housings can substantially damage the contacts during insertion into the housing. Furthermore, the possibility of imprecision in either the housing or the contacts could result in an unacceptable electrical connection with a circuit card or the like.
One prior art edge connector that has attempted to deal with certain problems resulting from miniaturization is shown in U.S. Pat. No. 4,479,686 which issued to Hoshino et al on Oct. 30, 1984. The connector of U.S. Pat. No. 4,479,686 was specifically directed to the problem of placing a large number of closely spaced apertures through a printed circuit board to receive the solder tails of the connector. In particular, the connector of U.S. Pat. No. 4,479,686, addresses the problem of closely spaced apertures in a printed circuit board by providing a single large rectangular aperture into which a portion of the base of an edge connector is seated. The edge connector shown in U.S. Pat. No. 4,479,686 includes two opposed injection molded halves which are secured to one another. The electrical contacts of the connector shown in U.S. Pat. No. 4,479,686 are mounted in the injection mold, and the connector half is molded around the respective contacts. Each contact is of generally U-shape with one leg of the U being bowed along a portion of its length. The bowed contact leg is disposed to lie within the card receiving slot of the connector. A portion of the straight leg of each U-shaped contact is imbedded in the injection molded plastic of the housing. However, a second part of the straight contact leg lies exposed adjacent the base of the connector housing. The conductive strips on the printed circuit board are disposed to abut against the exposed portion of each contact and are soldered thereto. The connector of the U.S. Pat. No. 4,479,686 requires an extremely complex molding process wherein each contact must be precisely positioned within the mold and held in that position during the high pressure injection molding process. Additionally, the contact is not optimumly configured to achieve the desired pressure on a circuit card disposed in the connector.
In view of the above, it is an object of the subject invention to provide an edge connector that is particularly well suited for closely spaced electrical contact and terminal arrays.
Another object of the subject invention is to provide an edge connector that facilitates the placement of the electrical terminals in the connector housing.
A further object of the subject invention is to provide an edge connector that provides a secure positively positioned mounting of the electrical terminals therein.
Still a further object of the subject invention is to provide an edge connector that provides improved centerline to centerline mating between edge card contact pads and the contact portions of the terminals in an edge card socket.